The present invention relates to a method of calculating a predictive shape of a wire structure for supporting a wiring design of the wiring structure, a calculation apparatus, and a computer-readable recording medium storing program for supporting the wiring design of the wiring structure such as a wiring harness.
In vehicles or the like, a plurality of electric parts and systems are installed, and these electric parts and systems are connected by so-called wiring harnesses which are wiring structures in which filament materials such as electric wires and communication lines are bundled up by bundling members such as an insulation lock or sheathing members such as tapes. As shown in FIG. 1, a wiring harness 1 has connectors 2a, 2b, 2c, 2d, which are adapted to be connected to electric parts and systems, mounted on respective end portions thereof. In addition, various types of clips 3a, 3b, 3c, 3d are mounted at intermediate portions of the wiring harness 1, and furthermore, the wiring harness 1 has a branch point 4. Note that respective constituent branch wires of the wiring harness 1 vary from one another in thickness, length, elasticity, density and the like due to constituent filament materials of the branch wires being different in number and kind.
Recently, to design a layout of such wiring harnesses on a vehicle or the like, in many cases, general purpose analytic software such as CAD (Computer Aided Design) and CAE (Computer Aided Engineering) has been used for computation, or engineers have used their experience and perception or sixth sense. However, there are many kinds and forms of wiring structures such as wiring harnesses, and therefore, it has been very difficult to design a layout of wiring harnesses while accurately estimating parameters including rigidities with respect to bending and twisting occurring at respective portions of the wiring harnesses only by depending upon the general purpose analytic software and the engineers' experience.
Then, the applicant of this patent application enabled the computation of a predictive shape of a wiring structure such as a wiring harness in consideration of physical characteristics of the wiring structure, that is, the material and rigidity with respect to bending and twisting occurring at respective portions of the wiring structure by making use of a finite element method disclosed in the following patent document No. 1, whereby the applicant proposed a method for supporting an optimum wiring design.
Here, documents that are referred to in this specification are as follows.
[Patent Document No. 1] JP-A-2004-139974
[Non-Patent Document No. 1] Matrix Finite Element Method (Pages 7 to 15) written by B. Nass and published on Aug. 10, 1978 by Brain Books Publishing Co., Ltd.
[Non-Patent Document No. 2] Building Structures Analysis Series II Analysis of Frame Structures (Pages 176 to 185) written by Shinya Tanishi and published on Dec. 20, 1976 by GIHODO SHUPPAN Co., Ltd.
While a method of JP-A-2004-139974 is superior in that a predictive shape of a wiring structure can accurately be computed in consideration of physical properties of the wiring structure, that is, the material and rigidity with respect to bending and twisting at respective portions of the wiring structure, it has been found that there still remains a room for further improvement.
Namely, since the method of JP-A-2004-139974 is such as to compute a predictive shape of the wiring structure by giving not only the physical characteristics of the wiring structure but also positions of a plurality of displacement destinations as restrictions to a finite element model, it has occurred depending on cases that a predictive shape cannot be computed accurately. For example, as shown in FIGS. 9A to 9C, assuming that a control point 1a8 of an initial shape of a wiring harness in which 1a0 constitutes a fixed point is displaced to 1z8 via 1b8 and 1c8 while avoiding an obstacle 30, it is understood that a shape 1b becomes a shape in which an influence of a stress (broadly speaking, referred to as a load) distributed in a shape 1a is reflected, and similarly, a shape 1c becomes a shape in which a stress distributed in the shape 1b is reflected, and a shape 1z becomes a shape in which a stress distributed in the shape 1c is reflected.
In the method of JP-A-2004-139974, however, since no computation is made in consideration of the influence of the stresses or loads distributed in the previous shapes, a further improvement is demanded in order to compute a predictive shape which is more realistic.